Filter discharger



Nov. 11, 1930. c. c. HERITAGE FILTERYDISCHARGER Filed Nov. 30, 1925 IEver! 702* 6: GZHE'P/TAGE. y Mia Patented Nov. 11, 193@ PATENT @FFICECLARK C. HERITAGE, OF. BUFFALO, NEW YORK, ASSIGNOR TO NATIONAL ANILINEd: CHEMICAL 00., 1N0, OF NEW YORK, N. Y., A CORPORATION OF NEW YORKFILTER DISGHARGER Application flied November 30, 1925. Serial No.72,161).

This invention relates to continuous filters and in particular tofilters of the drum type. It relates more particularly to a method andmeans for removing the filter-cake from the filter medium ofa continuousfilter of the drum type, especially in the filtration of crystallinematerial, or material which is pasty when wet. 7

Among the methods in use for removing o filter-cake from thefilter-cloth of a drum type of continuous filter, those principallyemployed comprise blowing the cake from the cloth by means of a gasunder pressure, and scraping the cake from-the cloth by means of 5 ascraper or doctor.

In order to release cake from the cloth of the drum type of continuousfilters by the former method, the thickness of cake must be greater thana certain minimumestablished by the tendency of the gas used to blow thecaketo blow holes through the cake instead of completely disengaging itfrom the cloth. This necessity as to thickness of cake greatly limitsthe use of continuous filters, for they must be operated at a slow speedto build up the required thickness of cake, or they must be periodicallystopped and cleaned, since the disengagement of the cake only in spotsgradually clogs the cloth and prevents further operation without athorough cleaning. On the other hand, a knife or doctor can not beeffectively substituted for the gas, because the nature of the cloth andits fastening prevent a continuous and uniform direct contact with itssurface.

I have discovered that if a roll be mounted to ride on the dischargeside of the filter drum and the roll be coated with a thin coating ofthe material to be removed, the cake will naturally cohere to the thincovering carried by the roll rather than adhere to the filter cloth. Theexcess of cake material so drawn by the roll from the cloth can beremoved readily by means of a scraper.

With the use of this discovery the limitations placed upon the filterspeed by the removing means is overcome, as it lends itself to theremoval of-thin layers of cake. Consequently the field of applicationfor continuous filters is greatly extended.

terial therefrom is the scraper 6.

As illsutrating an embodiment of the invention, reference is made to theaccompanying drawing, in which Fig. l is a partial end view of a filtershowing the discharger;

Fig. 2 is a side view of the structure shown in Fig. 1, and

Fig. 3 is a detail.

Near each end of the supporting frame 1 for the filter drum 2 isattached a pillow block 3. Pivoted on this block is an arm 4 whichcarries at its free end the roll 5 and the scraper 6 associatedtherewith. An extension 7 from the arm carries a weight 8 for causingpressure of the roll against the drum The pressure can be varied bysuspending the weight from any one of a number of holes 9 in theextension.

The roll 5 consists of a steel pipe 10 in each end of which trunnions 11are riveted. The trunnions rotate in the arms 4 and a bolt 12, with aninterposed washer 13, holds the roll in place at each end. The pipe iscovered with a chemical hose or equivalent fabric 14, and clamps 15secure the hose to the pipe.

Cooperating with the roll to remove ma- This scraper is L shaped incross section, one arm 16 contacting the roll 5. Trunnions 17 supportthe scraper in the arms 4, and a depending ear 18 has a slot 19 thereinwhereby the scraper can be adjusted relative to the roll 5 and held inadjusted position by means of a bolt 20 which extends through the slot19 and the arm 4 for the purpose hereinafter described.

In use, the roll is first covered by plasterin or wetting it with thematerial to be removed thereby forming in efiect a roll whose outersurface comprises said material. During this operation the materialbecomes puddled and its adhesiveness is apparently increased. The rollis then applied to the filter cake on the drum, the weight 8 is adjustedto give the desired pressure, the scraper is adjusted to scrape materialfrom the roll 5 while leaving discharging roll presses against the cake,the adhesiveness of the puddled cake on the roll draws the cake from thefilter cloth. The pivoted mounting of the roll-carrylng arms I permitsthe roll to yield with the cloth and thus continue in contact with thecake arried by it. The scraper or doctor in turn re- -moves from theroll the cake that has been abstracted from the'cloth.

The action of the roll is distinctly difierent from that of a gasblower, a suction device or a doctor knife, as the principle ofoperation which underlies the roll action is the greater naturalcohesion of the cake to itself than its adhesion to the filter cloth,and not the forcible separation of the cake from the vcloth.

I claim:

1. A method of removing a filter-cake of pasty material from acontinuous drum filter which comprises contacting said cake with amoving body of said material, whereby the cake is removed by cohesionwith the body of I material. I

2. A method of operating a continuous drum filter for material forming apasty filter-cake, which comprises passing the drum in contact withmaterial to .be filtered at a speed forming a thin pasty filter-cake,applying to the cake a roll coated with said cake material, therebyabstracting cake material from said drum, and removing from the roll thecake material abstracted from the drum.

3. A method of discharging a continuous drum filter which comprisesplastering a roll with material of the kind to be removed from the drum,applying the plastered roll to the cake of material carried on the drum,thereby abstracting said cake from said drum, and

removing from the roll cake material abstracted from the drum, whileleaving a coating of said material on said roll.

In testimony whereof I aflix my signature.

CLARK C. HERITAGE.

